Lock with readily interchangeable key

ABSTRACT

A key operated, permutation lock having a housing in which a pin plate support is slidably mounted and actuated by a lock bolt support. A back plate having openings to align with a pin plate support is positioned to be in registry with the pins when a proper key is inserted between the pin plate and the back plate. A stop lever prevents movement of the pin plate support until the lever is pushed aside by a properly fitting key.

[151 3,654,783 1 Apr. 11, 1972 United States Patent Sinclair S T N E m m a w w E T m A m w m w H N ..U M H Y n ma L B A E RG N mA 1H WC m MT Lm w Tm mbm wmm l BME 450 223 999 111 66 181 983 903 944 111 t e e r t S h t 4 4 l E N1 0% 3 3 l s h .M 2! mm m n a i 9 M 1 h 1 MH r 0 D. FN A n 0 m d e v M h F 1 .1 2 2 7 2 1 [21] Appl. No.: 24,594

Primary Examiner-Albert G. Craig, Jr.

Related US. Application Data [63] Continuation-in-part of Ser. No. 751,873, Aug.

Attorney-Stevens, Davis, Miller & Mosher 7] ABSTRACT A key operated, permutation lock having a housing in which a Pat. No. 3,505,841.

pin plate support is slidably mounted and actuated by a lock bolt support. A back plate having openings to align with a pin plate support is positioned to be in registry with the pins when a proper key is inserted between the pin plate and the back plate. A stop lever prevents movement of the pin plate support until the lever is pushed aside by a properly fitting key.

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8 Claims, 5 Drawing Figures LOCK WITH READILY INTERCHANGEABLE KEY This application is a continuation-in-part of my co-pending application Ser. No. 751,873, filed Aug. 12, 1968 now US. Pat. No. 3,505,841 dated Apr. 14, 1970. This disclosure of said parent application is hereby incorporated by reference and the present invention will be described as an improvement thereon.

This invention relates to locks and more particularly to key operated permutation locks having a pin-carrying plate member which moves horizontally when the bolt is retracted. A key and back plate have matching openings arranged so that when the key is in proper position it acts to guide the pins into the matching holes in the back plate so that the bolt can be retracted far enough so that the door can be opened.

In hotels and other commercial establishments it is often highly desirable to be able to quickly and easily change the key combination so that a previous possessor of a key cannot come back at some later time and open the door when someone else is renting the room. Since it is expensive to change the combination in most conventional pin cylinder locks, this safety measure is not practiced nearly as frequently as it should be.

The present invention avoids this difficulty by providing a key operated lock which is not only easy to change the combination thereof but also is very difiicult to pick or use a pass key in connection with it.

A principal object of the present invention is to provide a lock whose key can be readily changed but at the same time is secure against picking.

Another object of the present invention is to provide a lock which is capable of a very high number of key combinations by varying not only the shape and arrangement of the pins therein but also by varying the distance which segments of the back plate are laterally displaced by grooves in the key.

Other objects and advantages of this invention will become apparent upon a review of the attached drawings with the understanding that the invention is not confined to any strict conformity with the showing of the drawings but may be modified within the scope of the appended claims wherein:

FIG. 1 is a perspective view of the lock of the present invention viewed from the inside of the door showing a segmented back plate and a key positioned for entry into the front of the lock;

FIG. 2 is an elevational view from the rear of the lock showing both stops in place without the key;

FIG. 3 is an elevational view similar to FIG. 2 but with the key in place and the bolt turned to show alignment of the pins through the key into the back plate;

FIG. 4 is a top view of the embodiment shown in FIG. 3;

FIG. 5 is a plan view of the key and the back plate showing how the segments of the back plate are positioned when the key has forced them into alignment.

Referring now to the drawings in greater detail where like numbers are used to designate similar parts throughout the various views, the numeral refers to a lock structure in accordance with the present invention wherein a cam 12 is located within a support frame 14 so as to move that frame when the knob 18 and the shaft 16 are rotated in either direction so as to withdraw the bolt 20 from the strike plate 22. When frame 14 is moved, it carries pin plate support 24 with it along with pin plate 26 which has a plurality of pins 28 projecting from it. Pin plate is slidingly mounted in its support by grooves 25.

However, pin plate support 24 is restrained against movement by lock stops 30 and 31 which are bell crank shaped to pivot on pin 32 and biased by spring 34 so that end face 36 of the lock stop bears against a portion of pin plate support 24. The manner in which lock stops 30 and 31 prevent movement of the pin plate support and consequently the support frame, can best be seen in FIG. 2 where the key 38 is not in place.

Referring now to FIG. 3 which is an elevational view similar to FIG. 2 except with key 38 in place, it can readily be seen that the presence of a proper key causes lock stops 30 and 31 to pivot just far enough to permit sufficient clearance so that the pin plate support is free to slide to the right as viewed in FIG. 3. The entry of key 38 into the slot is facilitated by a slanting surface 40 on the leading edge of the key. (See FIG. 4.) If the key is a proper one, the holes 42 in the key and holes 44 in the segmented back plate will all be in alignment thus permitting entry of each of the pins 28 through both of these aligned holes so that the bolt 20 can be moved all the way to the right in order that the door may be opened upon turning of the knob 18.

The construction and operation of the slotted key in conjunction with the segmented back plate will now be explained in connection with FIGS. 1 and 5. As can be seen from these Figures back plate 41 consists of upper section 45, lower section 46 and center section 47. These sections are slidingly secured together by means of rivets 48 and 49 which are mounted in their respective elongated slots in order to permit said sliding movement. Normally the segments of the back plate are biased so as to remain in vertical alignment as depicted in FIG. 1. Key 38 has elongated grooves 50, 51 and 52 which will engage protuberances, usually the ends of the rivets, on at least one and preferably all of the three segments of back plate 41. The engagement of these grooves and protuberances will push the segments of back plate 41 out of alignment with each other as depicted in FIG. 5 thus exposing various holes 44 so that pins 28 can move directly through them. For example, in FIG. 5 hole 54 would normally be covered by upper segment 45 when all of the segments are in alignment. However, when key 38 pushed the segment out of alignment, hole 54 is exposed so that one of the pins 28 can enter it. Thus when all of the segments of the back plate 41 have been moved into proper registry position these holes will precisely line up with corresponding holes in the key to which that back plate is matched so that all of the pins 28 of the pin plate (which is matched to that particular key and back plate) will have holes in registry with them. It is thus necessary that each of the pins 28 not only have a hole in the key which is in re gistry with them but also that the key have grooves of the proper length so that when protuberances are engaged by ends of those grooves, the portions of the segmented back plate will be slid into proper alignment to expose the holes which correspond to the arrangement of the pins 28 on the pin plate and holes 42 on the key.

It is contemplated that not only can the number and size of the pins 28 be varied but also their arrangement and cross sectional configuration of each pin, the length of the grooves 50 in the key and the corresponding number, shape and arrangement of the holes in the segment back plate so that millions of different key combinations are possible.

Iclaim:

l. A key controlled lock comprising:

a. a housing having a keyhole;

b. a lock element movably supported with respect to said housing;

0. operating means associated with said lock element for shifting it to and from locking position; and

d. blocking means within said housing and accessible through said keyhole to control said shifting comprising:

1. a pin plate, carrying a plurality of pins located in predetermined positions and extending generally in the same direction, and carried by one of said housing and a part movable with respect thereto during shifting of said lock element;

2. an apertured plate, the apertures of which are so located and shaped as to closely receive said pins upon insertion of the proper key into said keyhole, and carried by the other of said housing and movable part;

one of said pin plate and said apertured plate being segmented, the segments being movably interconnected and biased to pin-aperture nonalignment position, said segments having key cooperating portions with at least one portion being more remote from said keyhole than at least one of said locations therein so that actuation thereof requires the key to extend beyond that location.

2. The lock of claim 1 wherein said blocking means comprises at least one lock stop biased to block the movement of said movable part.

3. The lock of claim 2 wherein said lock stop is a dog mounted adjacent said keyhole for movement to a nonblocking position upon insertion of said key.

4. The lock of claim 3 wherein said dog is a bell crank positioned to be pivoted by an edge of said key.

5. The lock of claim 1 wherein said segmented plate has at least two segments slidable relative to each other.

6. The lock of claim 1 wherein at least one of said segments has a protuberance engageable by a key to cause the preselected sliding registry thereof.

7. The lock of claim 6 wherein the protuberance is engaged by a groove in one side of a key.

8. The lock of claim 1 wherein said pin plate and said apertured plate are removably mounted in their respective positions for ready interchangeability with a second pin and apertured plate set to enable use of a difierent key. 

1. A key controlled lock comprising: a. a housing having a keyhole; b. a lock element movably supported with respect to said housing; c. operating means associated with said lock element for shifting it to and from locking position; and d. blocking means within said housing and accessible through said keyhole to control said shifting comprising:
 1. a pin plate, carrying a plurality of pins located in predetermined positions and extending generally in the same direction, and carried by one of said housing and a part movable with respect thereto during shifting of said lock element;
 2. an apertured plate, the apertures of which are so located and shaped as to closely receive said pins upon insertion of the proper key into said keyhole, and carried by the other of said housing and movable part; one of said pin plate and said apertured plate being segmented, the segments being movably interconnected and biased to pinaperture nonalignment position, said segments having key cooperating portions with at least one portion being more remote from said keyhole than at least one of said locations therein so that actuation thereof requires the key to extend beyond that location.
 2. an apertured plate, the apertures of which are so located and shaped as to closely receive said pins upon insertion of the proper key into said keyhole, and carried by the other of said housing and movable part; one of said pin plate and said apertured plate being segmented, the segments being movably interconnected and biased to pin-aperture nonalignment position, said segments having key cooperating portions with at least one portion being more remote from said keyhole than at least one of said locations therein so that actuation thereof requires the key to extend beyond that location.
 2. The lock of claim 1 wherein said blocking means comprises at least one lock stop biased to block the movement of said movable part.
 3. The lock of claim 2 wherein said lock stop is a dog mounted adjacent said keyhole for movement to a non-blocking position upon insertion of said key.
 4. The lock of claim 3 wherein said dog is a bell crank positioned to be pivoted by an edge of said key.
 5. The lock of claim 1 wherein said segmented plate has at least two segments slidable relative to each other.
 6. The lock of claim 1 wherein at least one of said segments has a protuberance engageable by a key to cause the preselected sliding registry thereof.
 7. The lock of claim 6 wherein the protuberance is engaged by a groove in one side of a key.
 8. The lock of claim 1 wherein said pin plate and said apertured plate are removably mounted in their respective positions for ready interchangeability with a second pin and apertured plate set to enable use of a different key. 